x86/setup: simplify initrd relocation and reservation

Currently, initrd image is reserved very early during setup and then it
might be relocated and re-reserved after the initial physical memory
mapping is created.  The "late" reservation of memblock verifies that
mapped memory size exceeds the size of initrd, then checks whether the
relocation required and, if yes, relocates inirtd to a new memory
allocated from memblock and frees the old location.

The check for memory size is excessive as memblock allocation will anyway
fail if there is not enough memory.  Besides, there is no point to
allocate memory from memblock using memblock_find_in_range() +
memblock_reserve() when there exists memblock_phys_alloc_range() with
required functionality.

Remove the redundant check and simplify memblock allocation.

Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Baoquan He <bhe@redhat.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Daniel Axtens <dja@axtens.net>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Emil Renner Berthing <kernel@esmil.dk>
Cc: Hari Bathini <hbathini@linux.ibm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Stafford Horne <shorne@gmail.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will@kernel.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Link: https://lkml.kernel.org/r/20200818151634.14343-14-rppt@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Author: rppt

arch/x86/kernel/setup.c

@@ -264,16 +264,12 @@ static void __init relocate_initrd(void)
 	u64 area_size     = PAGE_ALIGN(ramdisk_size);
 
 	/* We need to move the initrd down into directly mapped mem */
-	relocated_ramdisk = memblock_find_in_range(0, PFN_PHYS(max_pfn_mapped),
-						   area_size, PAGE_SIZE);
-
+	relocated_ramdisk = memblock_phys_alloc_range(area_size, PAGE_SIZE, 0,
+						      PFN_PHYS(max_pfn_mapped));
 	if (!relocated_ramdisk)
 		panic("Cannot find place for new RAMDISK of size %lld\n",
 		      ramdisk_size);
 
-	/* Note: this includes all the mem currently occupied by
-	   the initrd, we rely on that fact to keep the data intact. */
-	memblock_reserve(relocated_ramdisk, area_size);
 	initrd_start = relocated_ramdisk + PAGE_OFFSET;
 	initrd_end   = initrd_start + ramdisk_size;
 	printk(KERN_INFO "Allocated new RAMDISK: [mem %#010llx-%#010llx]\n",
@@ -300,26 +296,20 @@ static void __init early_reserve_initrd(void)
 
 	memblock_reserve(ramdisk_image, ramdisk_end - ramdisk_image);
 }
+
 static void __init reserve_initrd(void)
 {
 	/* Assume only end is not page aligned */
 	u64 ramdisk_image = get_ramdisk_image();
 	u64 ramdisk_size  = get_ramdisk_size();
 	u64 ramdisk_end   = PAGE_ALIGN(ramdisk_image + ramdisk_size);
-	u64 mapped_size;
 
 	if (!boot_params.hdr.type_of_loader ||
 	    !ramdisk_image || !ramdisk_size)
 		return;		/* No initrd provided by bootloader */
 
 	initrd_start = 0;
 
-	mapped_size = memblock_mem_size(max_pfn_mapped);
-	if (ramdisk_size >= (mapped_size>>1))
-		panic("initrd too large to handle, "
-		       "disabling initrd (%lld needed, %lld available)\n",
-		       ramdisk_size, mapped_size>>1);
-
 	printk(KERN_INFO "RAMDISK: [mem %#010llx-%#010llx]\n", ramdisk_image,
 			ramdisk_end - 1);